An in-vehicle apparatus such as a navigation apparatus displays a map of the vicinity of a present position on a display screen based on map data, and calculates an optimum route to a destination to thereby navigate the vehicle or driver. A storage medium to store the map data uses a hard disk drive. The hard disk drive, which has a large data volume, further stores music data, application software programs for operating the navigation apparatus, and image or audio data used in an audio function integrated into the navigation apparatus, in addition to the map data.
The navigation apparatus is further used as an in-vehicle multi-media system including the following functions: an output function to output an image or audio obtained from an external audio and video apparatus, such as TV, DVD, or a back monitor for capturing images in back of a vehicle during the backing operation; and an operation function to operate an on-screen operation panel window for in-vehicle apparatuses such as an air conditioner. Thus, in-vehicle apparatuses equipped with hard disk drives have been multi-functional.
The hard disk drive is a storage medium where data are written and read with a magnetic head on a disk to which magnetic materials are applied. During the operation of the hard disk drive, the disk rotating at a high speed rotates an ambient air to generate a pressure. The magnetic head thereby marginally floats above the disk. If the hard disk drive operates under the environment where surrounding atmospheric pressure falls remarkably, the air pressure floating the magnetic head is decreased and the gap between the disk and magnetic head cannot be maintained in the proper state. As a result, the magnetic head may collide with the disk to thereby damage it. Since an atmospheric pressure falls as an altitude rises, the hard disk drive has an application limit in altitude. Generally, the operation guarantee relative to the altitude for the hard disk drive is up to an altitude of 3000 m (about 0.7 atmosphere) to 5000 m (about 0.5 atmosphere).
The countermeasure for preventing damage of the hard disk drive mounted in the in-vehicle apparatus is thereby needed when used at a high upland area (e.g., than 3000, 4000, or 5000 meters) exceeding the guaranteed altitude where the operation of the hard disk drive is guaranteed.
Patent document 1 describes the following technology. When the relevant vehicle ascends up to a predetermined altitude (for example, 3000 m), some map data stored in the hard disk drive are copied or stored also into an external memory. The hard disk drive is then stopped; displaying a map is performed based on the map data stored in the external memory during the travel in the high upland area at an altitude not lower than 3000 m. Thus, such technology stops or disables the hard disk drive at a high upland area to thereby prevent the damage of the hard disk drive while allowing displaying the map.
Such a multi-functional in-vehicle apparatus equipped with a hard disk drive uses design images for display and guidance audio for explanation to users. Design images include various symbol marks, messages, and icons or switches for displaying GUI (Graphic User Interface) for a user to drive various functions. Output use data, which are used for outputting the design images or guidance audio, are needed as design image data or audio data, respectively. The output use data may be stored in the hard disk drive because of a large data volume. Therefore, if a part of the output use data for outputting images and audio stored in the hard disk drive is used for the function, which is assumed to be used at a high upland area, a countermeasure is needed to use the part of the output use data even when the operation of the hard disk drive is stopped.
However, Patent document 1 does not describe the countermeasure against such an event relating to the design image data or audio data.    Patent document 1: JP-2004-317385 A corresponding to U.S. Pat. No. 7,171,305